Enclose downloadUrl in downloadFile template

Author: derochs

runners/katacoda/templates/downloadFile.md

@@ -6,6 +6,6 @@ Create the directory <%= downloadDir %> if it doesn't exist.
 
 Download a file from '<%= downloadURL %>' and save it to the specified location '<%= downloadDir %>/<%= downloadFile %>'.
 
-`wget -c <%= downloadURL %> -O <%= downloadDir %>/<%= downloadFile %>`{{execute T1}}
+`wget -c '<%= downloadURL %>' -O <%= downloadDir %>/<%= downloadFile %>`{{execute T1}}
 
 <%= textAfter; %>